Rotary pump



E. e. COLLINS 2,670,690

ROTARY PUMP March 2, 1954 Filed NOV. 5, 1951 2 Sheets-Sheet l INVENTOR. E5927!" G Co/Zz'rzd' March 2, 1954 COLLINS 2,670,690

ROTARY PUMP Filed'Nov. 5, 1951 2 Sheets-Sheet 2 INVENTOR.

Patented Mar. 2, 1954 ROTARY PUMP Edgar G. Collins, Birmingham, Ala. 1 Application November 5, 1951, Serial No. 254,903

4 Claims.

This invention relates to a rotary pump; and it comprises in combination a pump casing having a closure plate mounted at either end of a cylindrical cavity therein, a shaft journaled in the closure plates with its axis coinciding with the axis of the cavity, a rotor comprising a pair of spaced parallel discs mounted adjacent the closure plates on said shaft for rotation therewith, the said rotor and casing defining an annular flow channel inside the pump casing through which liquid is impelled, means forming an inlet conduit opening into said annular channel, means forming a tangential outlet leading from said channel at a point spaced at least 18 from said inlet, an abutment closing off said channel located directly adjacent said tangential outlet on the far side thereof to prevent liquid from being recirculated, a plurality of propellers for impelling liquid from said inlet conduit through said peripheral channel and out of said tangential outlet; said propellers comprising a pair of arcuate arms mounted outside said rotary discs and pivoted at one end thereto, a bridging member connecting the free ends of said arms and an impeller element centrally mounted on said bridging member having dimensions corresponding to those of the cross section of said peripheral channel and adapted to impel liquid through the channel, and rollers mounted on the outer faces of said arms adjacent their free ends; and stationary cams mounted on the inner walls of said closure plates adapted to cooperate with said rollers to lift the impeller elements out of said peripheral channel and over said abutment as they reach the tangential outlet of the pump; all as more fully hereinafter set forth and as claimed.

In the prior art a large number of rotary pumps have been described in which pivoted propelling elements have been employed. Most of these have been provided with annular cavities with a rotor mounted eccentrically therein. Others have been provided with non-annular cavities having a greater radius along one side than the other to provide a conduit for the fluid to be pumped. In both of these types the impellers are moved slowly both inwardly and outwardly either by means of cams or by the impellers bearing against the peripheral wall of the cavity. Owing to the lack of any abrupt change in the direction of motion of the impellers it is possible to drive these prior art pumps at relatively high speed. They have come into widespread use for pumping non-viscous liquids in spite of their rather low efficiency.

Some of these prior art rotary pumps have been recommended for pumping concrete but after testing a number of the commercially available pumps I have come to the conclusion that none available at this time is satisfactory for this particular purpose. Concrete is so viscous that the usual rotary pump will completely fail due to cavitation if it is driven at a speed higher than about 30 revolutions per minute. When the prior art pumps are driven at speeds sufficiently slow to pump concrete their efficiency approaches zero.

I have discovered that on account of the slow speed which is necessary in the pumping of concrete and some other materials, particularly viscous liquids, it is possible to employ a new design of pump in which the cavity in the pump casing is cylindrical and the rotary member is mounted concentrically therein, a baflie or abutment being provided on the far side of but directly adjacent the outlet to prevent recirculation of the liquid and wherein means are provided to lift the impellers over the abutment just before they reach this element. The pump can be designed so that a rapid change in the direction of the motion of the impellers is produced and, of course, the closer the impellers approach the discharge opening before they are lifted to clear the abutment, the greater the efliciency of the pump. I have discovered thatit is possible to change the motion of the impellers rather abruptly from a rotary motion to a substantially linear motion as they approachthe discharge opening of the pump and' that this can be accomplished by the use of rollers mounted on the propellers with a cooperating cam mounted on the frame of the ump.

The linear motion is tangential to the axis of the pump rotor and may commence at a point where the leading edge of the impeller is aligned with the leading edge of the abutment so that as the former approaches the latter traveling in a substantially-straight line'clearance is obtained. From this point forward, the cam should becontoured in such fashion that the impelleris lifted over the trailing edge or heel of the abutment'after which it is released along a substantially linear path again to enter the flow channel of the pump. By use of the construction described it is possible to have the impellers occupy the full cross section of the flow channel of'the pump for at of their rotation. A high efliciency is thus obtained. V

' "My invention can be described in greater deleast half the period t tail by reference to the accompanying drawing which shows, more or less diagrammatically, a preferred embodiment of my pump. In this showing,

Fig. 1 is a vertical transverse section through the pump taken along the line l-l of Fig. 2,

Fig. 2 is a vertical section parallel with the axis of the pump taken along the line 22 of Fi 1,

3 is a perspective view of one of th p pellers used in'the pump, while Fig. 4 is a perspective view of cams used in the pump.

In the several views like parts are designated by the same reference numerals. Referring first to'Figs. 1 and 2, is formed from an annular central portion 3t with attached spaced parallel end plates l and 2 in which the pump shaft 3 is journaled. A pulley 4 may be secured to one end of the shaft to. serve as means for driving the pump. Rotor 5 is splinedto the shaft at 6.- The rotor com pri es two spaced. parallel disc I and 8. and eth r with the pump asing d fine an ann la flow channel 8 in the pump. The discs can be secured to the body oi he otor by means of screws. #3, if desir d. .An inlet condui such as hopper i0. is provided o i ed c n rete or ther viscous liquid into the flow channel. while ataheential outlet ll provided at a oint substantially 80 item the inlet. If desired the cross section of this outlet can be chan ed from quare to. round as indicated at $2. in F g- The p op lers. shown ge er l y at It, have a conru tion shown est in Fig. 3. They are form d with spaced parallel arms 15 which are pivoted at one end to the outside of the discs I and 8 at It. at the r ree ends the arms are ioined by a bridging member t! in. the center oi which an impelling element i3 is secured. The space b tween the rms and the imp ller c rr p nd o the thi kness of; the discs I and. 8,, he e discs ing slotted at I! to receive the bridging memer. of th P QPQHQ T and provide tor its pivotal motion. The front and back faces. of the hu pellers correspond in shape to. the crosssection or the flow channel and completely till this hannel \vhen'they are in he r operating posiion. Th se fr nt and back tacos are struck from an arc. whose center is at. the pivot. point it of one of the the propellers in. order to make. slots. I! as smelt.

as possible. In order to prevent recirculation of the concret back to the p ning an abutmerit 2.0 (Fi i) isprovided, the lowerfaee of which, forms the top of the outlet. conduit. The abutment completely blo ks the flow channel at. a point just beyond the outlet.

It. is necessary. of course, to provide means to lift. the impellers over the abutment, when they reach it during their rotation. For purpose rollers. 2|, can be provided on. the outside of the propeller arms, at their free ends, and oooperatingcams 22 mouhtedinside. the end plates of the, pump. 'lZhe operating. face ofthis. cam is provided. with, an arch-ate, section as at its. leading. end 40-, with a short substantially linear section 24, with a slightly raised portion 25 followed by another substantially linear sec.- ion. 26. Another short arcuate section it is prov ed t its. trailing end. As. will. be evident from astudy oi 1..., th arcuate section 2.3 oi the. cam. serves. to. convert, the. rotary motion of h mpell rs into a s bs antial y. linear motionalong the section II in such manner that the ee e ss .15 etiheinme e e t. clears t it is seen that the pump casing '4 leading edge 28 of the abutment. The hump 25 on the face of the cam serves to lift the impeller over the rear or heel of the abutment, while the remainder of the cam is designed to drop the impeller into its operating position as rapidly as possible without damage to the impeller. It will be seen that the impeller is in full operating position for at least of its rotary motion and that the completely inoperative period is very short. If this is compared with the conventional rotary pumps, it'will be seen that my impellers are fully operative for a considerably greater portion of their path with a consequent gain in eiiiciency.

' In order to prevent the concrete or other liquid from leaking into the space between the end plates and'the rotary discs of the pump, I provide what may be described as annular floating seals constructed of resilient material as shown at 29, the seals being mounted between the discs 1 and 8 and the end plates, as shown in Fig. 2. For the same purpose, wiping elements 30 are provided. around the impellers to prevent the concrete from entering. the Slots in which the impellers operate. The end plates can be attached to the annular casing Si by means of screws 3.2 or these elements can be welded togather.

While the shape of the impellers, as well as centrifugal force, both tend to hold the propellers in operating position in the flow channel, it is usually desirable to provide additional means for holding them in operative position, such as.

the springs. 34. These can be attached between the arms of the propellers and the discs I and 8 as shown in Fig. 1. The rotation of the pump rotor is in the direction of the arrows shown in Fig. 1.

While I have described what I consider to be the most advantageous embodiment of my pump it is evident. of course, that various modifications can be. made in the specific construction which has been described without departing; from the purview of this invention. The pump elements can be assembled in various ways within the skill of the art. Thus one of the propeller arms may be made detachable in which case the entire rotor including the discs 1 and 8 can, be cast inone piece, the detachable arm being secured to the bridging member ofthe propeller after assembly, for examplehy means ofscrews 33 (Fig. 3). It is possible to. place the inlet of. the pump somewhat farther irom the outlet in the direction of the-rotation than. is shown in Fig. 1 owing to the-tact, that the. impellers drop into operating position a considerable distance to the left of 'thehopper, but on the other hand it is usually more convenient to have the hopper at the top. of the pump and the. tangential outlet. at the bottom; It is possible,- ot course. to employ my pumpin the case oi all types or? viscous lieu-ids: and other materials aswell as of concrete. Viscous sludges and muds such as those encountered the mining industry. the sugar in.- dustry etc-are examples... Further modifications or. my nil-mp which fall, within the scope of the following claims will he immediately evident to those skilled in thisart...

What I claim is:

i. A. rotary pump, which comprises in 00mm nation a casing haying acylindrical cavity therein... closure-plates mounted at either end of the casing, a. shaft. iournaled in the closure plates with its. axi coinciding with the axis: of said cavity, a rotor. comprising a. pair of spaced par- 7li allel discs secured to said shaitfer rotation therewith, said rotor with the casing defining an annular flow channel for the liquid being pumped, means forming an inlet conduit leading into said flow channel, means forming a tangential outlet leading from said channel at a point spaced from th inlet at least about 180 in the direction of rotation, an abutment closing off said flow channel at a point adjacent the outlet on the far side thereof to prevent recirculation of the liquid, a plurality of propellers mounted on and spaced around said rotor for impelling liquid from the inlet conduit through said flow channel and out of said tangential outlet; said propellers comprising a pair of arcuate arms mounted outside said rotary discs and pivoted at one end thereto, a bridging member connecting the free ends of said arms and an impeller element mounted centrally on said bridging member having dimensions corresponding to the cross section of the flow channel and being adapted to operate in said flow channel to impel liquid therethrough; said arms being pivoted to said rotary discs at points in advance of the impeller elements so that the latter are pulled through said flow channel; and means for lifting the impeller elements out of said flow channel and over said abutment as they reach the tangential outlet of the pump.

2. The pump of claim 1 wherein said impeller elements have front and rear faces which are struck from arcs whose centers lie at the pivot point of the propeller arms.

3. A rotary pump which comprises in combination a cylindrical pump casing, closure plates mounted at either end of the casing, a shaft journaled in the closure plates with its axis coinciding with the axis of the casing, a rotor comprising a pair of spaced parallel discs secured to said shaft for rotation therewith, said rotor with the casing defining an annular flow channel, means forming an inlet conduit leading into said flow channel, means forming a tangential outlet leading from said channel at a point spaced at least about 180 from said inlet, an abutment closing oif said flow channel at a point adjacent the outlet on the far side thereof to prevent recirculation of the liquid, a plurality of propellers mounted around said rotor for impelling liquid from said inlet conduit through said flow channel and out of said tangential outlet; said propellers comprising a pair of arcuate arms mounted outside said rotary discs and pivoted at one end thereto, a bridging member connecting the free ends of said arms and an impeller element centrally mounted on said bridging member having dimensions corresponding to the cross section of the flow channel and being adapted to operate in said channel to impel liquid therethrough; said arms being pivoted to said rotary discs at points in advance of the impeller elements so that the latter are pulled through said flow channel; said bridging members and impellers operating in slots cut in said rotor to permit pivotal motion of the propellers, rollers mounted on the outer faces of said arms adjacent their free ends and stationary cams mounted on the inner walls of said closure plates adapted to cooperate with said rollers to lift the impeller elements out of said flow channel and over said abutment as they reach the tangential outlet of the pump.

4. The pump of claim 3 wherein packing means are provided around the slots of the rotor to prevent leakage of fluid from the flow channel and annular packing rings are provided between the rotor discs and the end plates to prevent leakage of fluid from the flow channel.

EDGAR G. COLLINS.

References Cited in the file of this patent UNITED STATES PATENTS (Addition to No. 661,868) 

